生物絮凝-罗非鱼养殖系统启动阶段絮体胞外聚合物、粗蛋白和总氨基酸变化

Changes of EPS,protein and amino acids in bioflocs during the start-up period of a biofloc system for tilapia cultivation

为了研究生物絮凝新吉富罗非鱼(Oreochromis niloticus)养殖系统的启动过程,本实验采用超声波法研究了该阶段絮体胞外聚合物(Extracellular Polymeric Substances,EPS)、粗蛋白和总氨基酸的变化情况。结果表明,控制养殖水体中溶氧在5 mg/L以上,水温25℃,由于碳源的添加不足,导致水体中硝酸盐发生积累;整个实验过程中,总磷的质量浓度持续增长;生物絮体的污泥活性指数(Sludge activity index,SVI30)先升高后降低;絮体中粗蛋白和总氨基酸含量不断增加,在第31天时,粗蛋白含量达到37.55%,与饲料中37.87%的粗蛋白含量接近,而总氨基酸含量达到了35%;絮体中EPS主要分松散附着的胞外聚合物(Loosely bound EPS,LB-EPS)和紧密粘附的胞外聚合物(Tightly bound EPS,TB-EPS),LB-EPS以多糖为主,而TB-EPS以蛋白质为主;实验过程中,LB-EPS逐渐降低,TB-EPS则先升高后降低。

To study the start-up process of biofloc system for tilapia cultivation,current research explored water quality and settleability of bioflocs,extracellular polymeric substances(EPS),crudeprotein and total amino acid changes during the start-up period of a bio-floc system for tilapia cultivation.The results showed that the nitrate concentration was accumulated for the lack of the carbon source in the cultivation,of which the dissolved oxygen was controlled at about 5 mg/L and the temperature was at 25℃.During the experiment,the total phosphorus was persistently raised;the bio-flocs sludge-sludge activity index(SVI 30)was at increased before decreasing.Crude protein and total amino acids content was increased.The crude protein content reached 37.55%in the 31st day,which was close to the content of 37.87%in the feed.The total amino acids content reached 35%.The EPS in bio-flocs mainly contained loosely bound EPS(LB-EPS)and tightly bound EPS(TB-EPS).LB-EPS and TB-EPS was mainly composed of polysaccharides and protein,Respectively.LB-EPS was gradually decreased during the experiment,while TB-TPS was increased be fore decreasing.